RU-ALLRUSSIAN 1971 Problem 12
Equally spaced perpendicular lines divide a large piece of paper into unit squares. N squares are colored black. Show that you can always cut out a set of disjoint square pieces of paper, so
that all the black squares are removed and the black area of each piece is between 1/5 and 4/5 of its total area.
Dataset text NuminaMath olympiads. Quoted with source.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.